---
name: write-a-skill-file
description: "Purpose, Rules, Inventory, Steps, Metrics: the five parts that let any agent do the job without guessing."
---

# Write a skill file in PRISM format

Purpose:: Write a skill file any agent can execute without guessing, in PRISM format.

Rules::
- Five parts in order: Purpose, Rules, Inventory, Steps, Metrics
- One purpose sentence; 3-4 rules; minimal inventory; 3-8 numbered steps
- Simple words, short lines, explicit scope; no fluff
- Self-contained: a fresh chat can run it with nothing else

Inventory::
- The job you keep explaining to your agent
- One past result you were happy with

Steps::
1. Write the purpose: the finished job in one sentence
2. Write 3-4 rules: quality bars and what is out of scope
3. List the inventory: only the files, tools and inputs the job needs
4. Write 3-8 steps a new agent can follow in order
5. Write the metrics: how you will judge the result and where you will review it
6. Re-read once as the agent; simplify every word you would stumble on
7. Save it as <name>.md

Metrics::
- You understand it in one read
- Another agent executes it without asking
- Scope is clear in all five parts

Source:: https://isklls.com/skills/write-a-skill-file (iSklls, free skill library)